A Golay cell is a type of electromagnetic radiation detector that consists of an enclosure containing an optic absorbing material and a flexible diaphragm or membrane. It works by converting absorbed optic radiation into heat causing the absorbing material to expand, resulting in a pressure rise that can then be detected. The conversion from radiation to heat has been accomplished via a membrane absorber which, in general, is not wavelength specific.
When using a Golay cell as a detector in, for example, a non-dispersive infrared (NDIR) gas detection, it is valuable for the Golay cell to have high spectral correlation with the target gas. One approach is to fill the cell with IR absorbing gases that have the same or similar absorption spectrum as the target gases.
However, in comparison with a membrane absorber, a gas absorber has much less molecular density, thus a much thicker layer of gas is needed to achieve sufficient absorption. In addition, when the same level of absorption is achieved, the gas layer would possess a larger heat capacity than a solid membrane, thus lower temperature rise and sensitivity.
In many applications, it is also desirable for the detector to have a planar, or a small overall form factor, which is difficult to implement when the gas absorber demands a long optical path length. Alternatively, although a membrane absorber with an external filter would provide the spectral selectivity, it tends to be expensive and the filters are often sensitive to the angle of the incoming light.